1. Field of the Invention
This invention relates to a process for the preparation of copolymers of vinyl acetate and a fluoromonomer. More particularly, this invention relates to a process for preparing copolymers of vinyl acetate and a fluoromonomer having a substantially alternating distribution of the recurring monomeric units derived from vinyl acetate and the fluoromonomer along the polymer backbone.
2. Prior Art
Typical copolymers based on tetrafluoroethylene or chlorotrifluoroethylene are disclosed in U.S. Pat. Nos. 3,624,250; 4,123,602; 3,642,742; 4,513,129; 3,445,434; 3,847,881 and 2,468,664. U.S. Pat. No. 4,434,273 discloses perfluorovinyl ethers and copolymers of such materials with tetrafluoroethylene. U.S. Pat. Nos. 4,471,076 and 4,500,739 disclose fluorocarbon polymers containing carboxy groups. U.S. Pat. No. 4,513,129 discloses copolymers of ethylene, tetrafluoroethylene or chlorotrifluoroethylene and fluorovinyl compounds of the formula H.sub.2 C=CFR.sub.f where R.sub.f is a fluoroalkyl group of C.sub.2 -C.sub.10.
U.S. Pat. No. 4,482,685 discloses that copolymers of ethylene and chlorotrifluoethylene have been polymerized in an aqueous emulsion using free radical initiation. The free radical initiators include a wide variety of peroxide and oxidation-reduction systems. The polymer composition can be adjusted by either the ethylene pressure or the reaction temperature. The physical or mechanical properties of the copolymers formed depend not only on the polymer composition but also on the degree of alternation of the monomers.
It is known to emulsion polymerize a variety of fluoropolymers. U.S. Pat. Nos. 3,857,827 and 4,025,709 disclose the emulsion polymerization of polyvinylidene fluoride. U.S. Pat. No. 4,225,482 discloses the emulsion.
Improved barrier resistance of ethylene vinyl alcohol copolymers is disclosed in U.S. Pat. No. 4,427,825 and the Background of the Invention thereof, as well as related U.S. Pat. No. 4,468,427.
The above review of the art shows a great variety of fluoropolymers and copolymers. Modena, et al. Vinyl Acetate and Vinyl Alcohol Copolymers with Tetrafluoroethylene, European Polymer Journal, 1967, Vol. 3, pp. 5-12, Pergamon Press Limited, England (1967) discloses a specific class of copolymers of vinyl acetate and vinyl alcohols. Copolymers of tetrafluoroethylene and vinyl acetate are disclosed in Great Britain Patent 583,482. U.S. Pat. Nos. 3,006,881 and 3,043,823 disclose the emulsion polymerization of polychlorotrifluoroethylene.